Headlights for motor vehicles create an illumination beam projected forward of the vehicle to illuminate the road. In order to avoid glare for oncoming traffic, the intensity distribution of the illumination beam for low beam light comprises a bright/dark boundary. Regulations pertain to the specific required shape of the bright/dark boundary, which generally includes a horizontal portion and an inclined portion.
Different lamps of the incandescent type exist for motor vehicle headlights. While some lamps only comprise a single filament as light-emitting element, other lamps, such as e.g. H4, comprise two filaments and a baffle arranged proximate to a first filament to partially shield light emitted therefrom. With such two-filament types of lamps, both high beam and low beam function may be achieved by the same lamp and reflector.
Examples of known two-filament lamps are H4, HS1, and the newly proposed H19.
WO2014207112A1 discloses such a two-filament lamp for a vehicle headlight, with the filaments in a transparent lamp vessel with a partial color filter for coloring a peripheral and/or a scattered portion of light of the lamp while leaving the lamp's illumination beam uncolored.